The offense, which under the Finnish criminal code is committed when someone causes long-term, wide ranging and serious damage to the environment, carries a maximum custodial sentence of six years.

The leak of nickel and other industrial sulfates was discovered at the start of July at the Harjavalta mine near Pori, western Finland, which sits on the bank of the Kokemäki river.

The mine is operated by Norilsk Nickel, and represents the largest nickel spillage on record in Finland’s history.

Pori City Council says that people should not eat fish from the Kokemäki river until sample fish have been tested for nickel levels.

The police examination is being carried out alongside other official bodies who are investigating the environmental impact on the area, including southwest Finland’s regional development agency, also known as an ELY center.

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